The present invention relates to a skin whitener composition containing mercaptodextran for external use and to a method of whitening skin by topically applying a composition containing an effective amount of mercaptodextran.
In Asia, most women desire whiter skin because of traditional beliefs that white skin denotes nobility and aristocracy. Skin color is primarily determined by the amount of melanin present in the skin. Thus, in recent years, cosmetic compositions have been developed to reduce the amount of melanin in the skin and therefore, whiten the skin. These development efforts have focused on whitening agents that inhibit the function and activity of tyrosinase, which plays a key role in the biosynthesis of melanin. For example, it has been proposed to incorporate into cosmetic compositions tyrosinase activity inhibitors such as hydroquinone, vitamin C and its derivatives, kojic acid, arbutin, glutathione, cysteine, and mulberry extract, among others.
In addition, thiolated materials such as mercaptosuccinic acid and mercaptoethanol have been proposed. The problem with these materials, however, is that due to the thiol moiety, the products have an objectionable odor that makes such a product undesirable to a consumer. Moreover, such materials are generally difficult to incorporate into water containing cosmetic formulations due to solubility difficulties.
Thus, despite the efficacy of the above compounds in producing a whiter skin, alternatives are continually being sought. The present inventor has now found that mercaptodextran is an effective skin whitening agent. Moreover, the mercaptodextran has a less objectionable odor and does not suffer from the solubility problems of the other known thiol containing whitening agents. It is also believed that the skin whitening effects of other known whitening agents can be enhanced by the addition of mercaptodextran.